Endurance Training - What 4 Metabolic Adaptations Occur?

Performing endurance training can cause different metabolic adaptations to occur. The 4 metabolic adaptations that occur from endurance training include...

1. Increased VO2max - increased capacity for oxygen consumption by the mitochondria "powerhouse of the cell"
2. Increased capacity to store muscle & liver glycogen
3. Increased rate of fat oxidation with decreased glycogen utilization during exercise at all work loads
4. A shift in the lactate turn point to a higher running speed or % VO2max

Why & how do these adaptations occur?

Increased Number Of Blood Capillaries

There is an increase in the number of blood capillaries surrounding the muscle fibers that occurs with training. The more blood that gets transported to the muscle through these capillaries, the more oxygen & fuel that can be transported to the muscles' mitochondria. The more oxygen and fuel, the more fat oxidation that occurs through your training and work outs!

Adaptations in Metabolic Pathways - High Intensity Training & Low Intensity Training

In high intensity training (threshold & speed work outs) increases your body's ability to use liver and muscle glycogen as a fuel source during training and you body to maintain exercise intensity despite low intracellular pH. Your muscle adapts by increasing it's ability to buffer the pH in your muscle.

In low intensity training (aerobic base training) important adaptations occur in the mitochondria of the muscle cell. Training alters your mitochondria's composition by increasing the number and size. There is an increase in the enzyme concentrations that are associated with fatty acid metabolism. Additionally there is an increase in your muscle's resting storage of glycogen (stored carbohydrate in the muscle & liver), triglycerides (stored fat), and myoglobin (oxygen carrying pigment in muscle). Increase in your muscle's glycogen storage happens in early stages of training (4th day).

A Shift in the Lactate Turn Point

With an increase in mitochondrial enzyme content, there is an increase rate of fat oxidation and a shift in the lactate turn point. During exercise, if you are untrained and/or you are working out at a higher intensity, your carbohydrate metabolism kicks on and your body uses carbohydrate (stored muscle & liver glucose - glycogen) as a fuel source. As your body adapts to training and the size and number of mitochondria increase, your body can oxidize "burn" fat at a higher intensity and your body is less dependent on carbohydrates for a fuel source. Fat can provide more energy at higher exercise intensities than it could before, with less need to activate carbohydrates as a fuel source. By using more fat, lactate production with be reduced during training. To lose fat, you must be able to burn fat!

Training at the right intensities and progressing your volume each week can cause great adaptations to your body's cellular metabolism and make your body much more efficient! A more efficient metabolism, a more efficient you and your body!

Feel free to post or ask questions!

Happy Active Metabolism, Happy Running! :)